For example, numerous insulated electrical wires are installed in automobiles, and lighter-weight insulated electrical wires have been sought to respond to the demand for lighter-weight vehicles.
Typical insulated electrical wire is constituted of a conductor in which electrically conductive core wires (filaments) are bundled, and an insulating resin covering which covers the conductor. Up to now, conductors constituted of core wires made of copper or copper alloy (called “copper conductors” hereinafter) having excellent electrical conductivity have been generally used.
In contrast, to respond to the demand for lighter weight as mentioned above, an aluminum electrical wire that uses a conductor in which core wires made of aluminum or aluminum alloy (called “aluminum-based core wires” hereinafter) are bundled is proposed in Patent Document 1, and this aluminum electrical wire is described as being light-weight compared to insulated electrical wire that uses a copper conductor of the same diameter.
However, the electrical conductivity of an aluminum conductor is lower than that of a copper conductor (approximately 60%), and the cross-sectional area of an aluminum conductor must be greater than the cross-sectional area of a copper conductor in order to assure electrical conductivity similar to that of an insulated electrical wire constituted of a copper conductor.
In this way, in aluminum electrical wires having an aluminum conductor that assures electrical conductivity similar to that of a copper conductor, the outer diameter of the aluminum electrical wires is larger because the cross-sectional area of an aluminum conductor is larger than that of a copper conductor, that is, the cross-sectional diameter is larger. Specifically, by setting the thickness of an aluminum conductor to from approximately 1.5 to 1.7 times the thickness of a copper conductor, an electrical wire having similar current capacity and similar electrical conductivity can be obtained.
When the outer diameter of the electrical wire is large, the connecting portion between the electrical wire and the terminal such as a crimping portion on the crimping terminal to which the insulated electrical wire is connected becomes large, and there is the risk that the terminal can no longer be inserted in the cavity (terminal insertion hole) in the connector housing of the connector constructed by mounting the terminal.